I sync all my calendars with iCloud [actually, a mixture of external calendars synced to Google, then synced to iCloud]. But it's SO much simpler to get true three-way sync between iPhone, Web and Apps with iCloud than it was with Google (and for whatever reason, I prefer apps to webpages. Color me old-fashioned).

So, yeah, I use it. Notes, reminders, Messages, Contacts, etc. All work very well.

For the past year, I used Google for mail/calendars/contacts, and iCloud for notes/safari/documents/find my x. This somewhat worked. A handful of my contacts kept getting duplicated (to something on the order of 100 instances). I got fed up with this behavior last week and migrated contacts over to iCloud. So Google gets mail and calendars. I'll see how it works out, but based on this past week, I'll continue to run with this setup for some time to come.

FWIW I have an iPhone. But some of the contact behavior was *very* strange. Like a long time phone contact loses the phone number then gets duplicated 100x. Or half of my new contacts being renamed after I've added them on my phone. For example I add a contact on my phone with the last name is put in as "Smith (medicine intern)", which Google later renames to middle: "Smith (medicine" Last: "intern)"

i only use it for calendars (girlfriend and i share calendars) and find my iphone. the rest of the stuff i dont use because its all saved to my computer daily anyway.

i also have icloud sync set to manual (settings - mail, contacts, calendars -fetch new data - push is off, fetch hourly, advanced - icloud is set to manual). this way my battery life doesnt get murdered and i only see new entries in my calendar if i actually open the calendar app.

Use google drive for docs, drop box for sharing world backups on my minecraft server. That's it. iCloud sucks and is WAY too small for anything useful. I didn't like skydrive. Backups I tried we're backblaze and crash plan. Backblaze wouldn't install on server OS and crashplans restore was unbearably slow (we are talking 300 gb restore taking 3 MONTHS because it wouldn't go faster than 512Kbps from a local FIREWIRE drive). I do like google drive though, I find myself creating a new doc for something every other week or so.

Use it for my ipad, that is it is turned on. However I don't really need it, I don't put photos..etc on it nor contacts...I still do the pen and paper thing for a lot of stuff.
actually I can grab a pen and small notepad and write stuff down far faster than I can get into an ipad app and fill out boxes that's for sure.

__________________Hexen was just a crappy doom clone with level designs that defy all common sense and logic to an infrastructure in a poor effort to do little more than provide a false sense of exploration in what is nothing more than lots of boxed rooms put together from some guy drawing squares on grid paper before creating it in the engine editor..... like most old 3d games did. If you tried to build such in real life, more than half the infrastructure would completely collapse in on itself.

I really only used it recently when I decided to get an iPhone 5. I turned it on for my 3GS. The day that I activated my iPhone 5, everything was automagically on my new phone exactly like it was on my old phone. Photos, app settings, app data. Call me psyched. I haven't tried it on the Mac yet.

used it after setting up imessages on the ipad. wanted to get the contacts over from the phone so turned on icloud sync for contacts on the phone, turned it on on ipad and done. then turned it off again.